Old bore's tunnel vision recycled

A derelict tunnel built by "vicious, drunken and idle" convicts in the early 19th century may be reopened as part of a project to irrigate Sydney's public parks and gardens with waste water.

Instead of being flushed out to sea, stormwater, seepage and run-off from several tunnels - including the old convict tunnel - would be upgraded to "grey" water and used to replace much of the 300 or so megalitres of drinking-quality water used annually in the Botanic Gardens, The Domain and Hyde Park.

The project - named Busby's Bore after the engineer, Major John Busby, and his tunnel - is the brainchild of Clean Up Australia founder and chairman Ian Kiernan, who first started exploring the underground possibilities a decade ago.

"It represents a fantastic opportunity to showcase strong commitment to a sustainable environment in Sydney," said Mr Kiernan, who is in talks with several leading public and private stakeholders, including City of Sydney, Sydney Water, RailCorp and the Botanic Gardens.

Busby's Bore was commissioned in 1827 to supplement Sydney's original supply of drinking water from the increasingly polluted Tank Stream. It ran, much of the way through solid rock, from Lachlan Swamp in what is now Centennial Park, into a reservoir at the Oxford Street end of Hyde Park.

Progress was reportedly so slow - due as much to poor ground conditions as bad management and a recalcitrant workforce - that townsfolk came to refer to Major Busby, unfairly, as the "Great Bore". Finally completed in 1837, it served the city for almost 60 years before becoming contaminated.

Engineering historian Jon Breen points out that before it was decommissioned in the 1890s, the four-kilometre bore was briefly used to irrigate the Botanic Gardens.

"But the city fathers became concerned that children might drink from the ponds, and the bore was closed," said Mr Breen, who hosts occasional walking tours of the bore.

The next, scheduled for April 28, takes in the original source at Busby's Pond, a memorial cairn in Centennial Park and an entrance shaft, one of many around the city, now on the site of Fox Studios.

The new project envisages water being treated at a modern new plant, then stored in an old railway tunnel which would be converted into an "under city dam".

Conveniently, it lies beneath the Botanic Gardens' main pumping station.